Abstract: Disclosed is a method to reduce external signal interference with signals in a computer disk storage system including a disk drive. An electrically conductive housing is provided for the disk drive to enclose and support within the housing analog circuitry, a motor for rotating media for the storage of information, and circuitry for converting analog signals to digital signals. Circuitry and conductors which carry analog signals are enclosed within the electrically conductive housing and signal conversion circuitry is provided within the housing to convert analog signals into digital signals before transmission to the exterior of the housing.

Abstract: An enhanced method and system for unloading magnetic heads are disclosed. The system limits the maximum and minimum speed of the actuator while unloading the heads during a power failure. A BEMF control circuit monitors the velocity of the actuator using the BEMF of the actuator as a gauge of the velocity. The BEMF control circuit uses a sense resistor to remove the inherent resistive component of the actuator from its BEMF measurement. If the velocity of the actuator increases above a safe level the BEMF control circuit decreases actuator current to prevent further acceleration. If the velocity of the actuator decreases below a safe level the BEMF control circuit increases the actuator current to accelerate the actuator to a safe level.

Abstract: Disclosed is a rigid disk drive information storage device which includes a rigid disk having an outside diameter in the range of about 33-34 mm., with a housing having a footprint that includes a width of about 35 mm. and utilizing a rotary actuator for positioning read/write recording elements across the surface of the disk. The disk storage devices further includes a footprint with length of about 50.8 mm., and includes in one embodiment dynamic head loading apparatus for loading the read/write recording elements into operative relationship with the disk. In another embodiment the rigid disk drive utilizes contact start stop loading and unloading of the read/write recording elements. An inertial latch is also provided for preventing rotation of the actuator when the drive is subjected to a rotational force.

Abstract: Disclosed is a rigid disk drive information storage device which includes a rigid disk having a diameter in the range of about 45-50 mm., with a housing having a footprint that includes a width of about 51 mm. and utilizing a rotary actuator for positioning read/write recording elements across the surface of the disk. The disk storage devices further includes a footprint with a length of about 70 mm., includes dynamic loading apparatus for loading the read/write recording elements into operative relationship with the disk and further includes an inertial latch for preventing rotation of the actuator when the drive is subjected to a rotational force.

Abstract: A method for optimizing the storage capacity of miniature disk drives without affecting reliability or yields of the disk drives uses an iterative seek process to define track zero. Initially, a physical reference point is defined and a transducer is moved in coarse steps from the physical reference point until interference with a stationery loading ramp or other mechanical component, hereinafter, "ramp," is detected. Upon detection of interference, the transducer is moved one coarse step away from the ramp and then the transducer is moved in fine steps towards the ramp until interference is again detected. Upon detection of interference, the transducer is moved away from the ramp a predetermined distance. After the transducer is moved the predetermined distance, a check is made for interference. If interference is detected, the transducer is moved in fine step towards the center of the disk until interference is no longer detected.

Abstract: An embedded servo system for a disk drive is disclosed. An asymmetrical position sub-field reduces the overhead of the disk position system. The sub-field includes at least two normal frame pairs and only one quadrature frame pair interleaved with one of the normal pairs to form the asymmetrical position sub-field. The prerecorded embedded servo information in each track of the disk includes a multiplicity of different length servo fields, i.e, each track includes at least two types of servo fields where the first type has a first length and the second type has a second length that is different from the first length. The length of a servo field refers to the number of prerecorded bytes in the servo field. The multiplicity of different length servo fields includes a first type having a full track address sub-field and a second type having a modulo track address sub-field in place of the full track address sub-field.

Abstract: Disclosed is a disk drive information storage device having a housing and a disk means for recording and reproducing information. The disk drive information storage device utilizes an actuator comprising a body portion supported by the housing for rotation about an axis, and a load beam connected to the body portion for rotation of a first end of the load beam in a plane substantially parallel to a surface of the disk means. The load beam includes an elongated lift tab having a free end which extends beyond the first end of the load beam, with the lift tab extending along an axis which is skewed from the centerline of the load beam. A slider body including a transducer for recording and reproducing information from the disk is supported by the load beam at a position intermediate the first end of the load beam and the axis of rotation of the body portion.

Abstract: A spin motor control system includes a BEMF commutation circuit, a startup circuit and a monitor circuit, each of which operate utilizing digital techniques. The BEMF commutation circuit includes first and second counters that are programmable to accommodate for changing system parameters. The BEMF commutation circuit does not require the incorporation of an external capacitor, is insensitive to leakage current, and provides stable timing characteristics. The startup circuit also includes a counter and is programmable to accommodate for changing system parameters. The startup circuit does not require an external capacitor and provides stable generation of the startup pulses. The monitor circuit includes first and second counters for blanking the BEMF circuitry after commutation. The monitor circuit further includes circuitry for detecting and correcting the direction of rotation of the spin motor.

Abstract: In an embedded servo system for a disk drive, prerecorded servo information in each track of the disk includes a multiplicity of different length servo fields. Each track includes at least two types of servo fields where the first type and the second type have different lengths. The length of a servo field refers to the number of prerecorded bytes in the servo field. The multiplicity of different length servo fields includes a first type having a full track address sub-field and a second type having a modulo track address sub-field in place of the full track address sub-field. One embodiment includes the first and second types of servo fields and a third type of servo field. The third type of servo field includes only track following information and no track address information. The servo fields of differing lengths are interleaved in each track of the disk. The servo fields are chosen to provide a high seek sampling rate in comparison to the required performance and a reduction in the servo overhead.

Abstract: A computer having a hard disk drive includes a battery voltage monitor which establishes a shut down condition of the computer if the supply voltage falls below a chosen level V.sub.L. Upon start up of the hard disk drive motor, current through the motor is limited so that supply voltage of the battery to a computer does not fall below level V.sub.1, which level is greater than the level V.sub.L. Additionally during start up, current in the motor is controlled so that voltage supplied by the battery to the computer does not rise above a threshold level V.sub.2 which is greater than V.sub.1.

Abstract: Disclosed is a disk drive information storage device which includes a disk for recording and reproducing information, with the disk drive information storage device having a housing with a baseplate which includes a peripheral portion having a lip which extends circumferentially around the peripheral portion and the cover also includes a peripheral portion with a free edge at the periphery of the cover such that when the baseplate is engaged with the cover the overlap of the free edge of the baseplate and the free edge of the lip provides shielding to the internal components of the disk drive from electromagnetic interference, which my be present in the environment in which the disk drive is utilized. The disk utilized in the disk drive has a diameter in the range of from about 45 mm to about 50 mm. The housing of the disk drive has a first external dimension of about 51 mm and a second external dimension of about 70 mm.

Abstract: Disclosed is a disk drive information storage device having a housing and a disk means for recording and reproducing information. The disk drive information storage device utilizes a spin motor control system having a start-up control circuit which includes a counter and is programmable to accommodate for changing system parameters. The start-up control circuit does not require an external capacitor and provides stable generation of the start-up pulses. The spin motor control system also includes a BEMF commutation circuit which operates utilizing digital techniques. The BEMF commutation circuit includes first and second counters that are programmable to accommodate for changing system parameters. In one embodiment, the housing has a first external dimension of about 51 mm. In another embodiment, the disk means has a diameter in the range of from about 45 mm to about 50 mm.

Abstract: Disclosed is a disk drive information storage device which, in one embodiment, includes a disk having a diameter in the range of about 45 to 50 min., with a housing and a spin motor. In another embodiment, the disk drive information storage device includes a disk, a housing having a first external dimension of about 51 mm., and a spin motor. The spin motor includes a rotor and a stator, with either the rotor or the stator having a plurality of winding structures associated therewith, and the other having a plurality of magnetic poles. Each winding structure is made up of two winding portions, with only one winding portion being used to drive the rotor relative to the stator upon drive currents being applied to the winding structure, but with both winding portions being used to generate back electromotive force when drive current is cut off from the winding structure. This generated electromotive force is used to actuate an actuator drive motor to unload the read/write heads from the disk surface.

Abstract: A spin motor control system includes a BEMF commutation circuit, a startup circuit and a monitor circuit, each of which operate utilizing digital techniques. The BEMF commutation circuit includes first and second counters that are programmable to accommodate for changing system parameters. The BEMF commutation circuit does not require the incorporation of an external capacitor, is insensitive to leakage current, and provides stable timing characteristics. The startup circuit also includes a counter and is programmable to accommodate for changing system parameters. The startup circuit does not require an external capacitor and provides stable generation of the startup pulses. The monitor circuit includes first and second counters for blanking the BEMF circuitry after commutation. The monitor circuit further includes circuitry for detecting and correcting the direction of rotation of the spin motor.

Abstract: A spin motor assembly of a disk drive apparatus includes a stator having a plurality of wound coils associated therewith, and a rotor having a plurality of magnetic poles. Each winding structure of the stator is made up of two winding portions, with only one winding portion being used to drive the rotor relative to the stator upon drive current being applied to the winding structure, but with both winding portions being used to generate back electromotive force when drive current is cut off from the winding structure. This generated electromotive force is used to actuate an actuator motor to unload the read-write heads from the disk surface. As an alternative, each winding structure of the stator is made of a single winding, and the winding structures are used successively to drive the rotor relative to the stator, but with at least two winding portions generating back electromotive force when drive current is cut off.

Abstract: The rotor of a brushless DC motor is monitored continuously, and successive positions thereof are encoded in the form of digital counts. The count is continuously converted to analog form, and is compared with an analog reference signal, to determine the position error, and hence the speed error, or the motor relative to the desired constant speed reference. The error differential is suitably converted back to digital form to provide the motor power/drive amplifiers with sufficient electrical drive for the degree of correction which must be made. The digital position count from the counter is also coupled to a memory, which maintains in storage representations of position, and torque characteristics of the motor. Hence, based on these stored quantities and upon the actual motor parameters as exemplified by the present position, the memory issues control signals, that is timing and directional commands for correction of the motor speed.